Prediction ofBurkholderia pseudomalleiDsbA substrates identifies potential virulence factors and vaccine targets

Abstract

<jats:title>Abstract</jats:title><jats:p>Identification of bacterial virulence factors is critical for understanding disease pathogenesis, drug discovery and vaccine development. In this study we used two approaches to predict virulence factors of <jats:italic>Burkholderia pseudomallei</jats:italic>, the Gram-negative bacterium that causes melioidosis. <jats:italic>B. pseudomallei</jats:italic> is naturally antibiotic resistant and there are no melioidosis vaccines. To identify <jats:italic>B. pseudomallei</jats:italic> protein targets for drug discovery and vaccine development, we chose to search for substrates of the <jats:italic>B. pseudomallei</jats:italic> periplasmic disulfide bond forming protein A (DsbA). DsbA introduces disulfide bonds into extra-cytoplasmic proteins and is essential for virulence in many Gram-negative organism, including <jats:italic>B. pseudomallei</jats:italic>. The first approach to identify <jats:italic>B. pseudomallei</jats:italic> DsbA virulence factor substrates was a large-scale genomic analysis of 511 unique <jats:italic>B. pseudomallei</jats:italic> disease-associated strains. This yielded 4,496 core gene products, of which we hypothesise 263 are DsbA substrates. Manual curation of the 263 mature proteins yielded 73 associated with disease pathogenesis or virulence. These were screened for structural homologues to predict potential B-cell epitopes. In the second approach, we searched the <jats:italic>B. pseudomallei</jats:italic> genome for homologues of the more than 90 known DsbA substrates in other bacteria. Using this approach, we identified 15 potential <jats:italic>B. pseudomallei</jats:italic> DsbA virulence factor substrates. Two putative <jats:italic>B. pseudomallei</jats:italic> virulence factors were identified by both methods: homologues of PenI family β-lactamase and of succinate dehydrogenase flavoprotein subunit. These two proteins could serve as high priority targets for future <jats:italic>B. pseudomallei</jats:italic> virulence factor characterization.</jats:p>